Gas sensors which are designed to measure the concentration of a given gas component contained in a measurement gas have as sensor device which is made up of a solid electrolyte body and a pair of electrodes disposed on the solid electrolyte body and whose tip is disposed in a pipe through which the measurement gas flows. The sensor device has lead wires which are joined to the electrodes and extend from a base end thereof. Springs (which will also be referred to below as electrode springs) are placed in contact with the electrodes of the sensor device using an elastic force. The lead wires are connected to the electrodes through the electrode springs.
For example, Japanese Patent First Publication No. 2001-188060 discloses a gas sensor equipped with a plurality of metallic terminals which are disposed in terminal housing holes of a porcelain insulator and placed in contact with terminal electrodes disposed on a base end of a sensor device. The metallic terminals are each made up of a first portion contacting with the porcelain insulator and a second portion which is bent obliquely from the first portion and contacts with the terminal electrode. An elastic pressure is exerted on the second portion to achieve the contact with the terminal electrode.